Liquid phase polymerization of olefins using a boria-alumina catalyst



March 28, 1967 OVERHEAD TEMPERATURE LIQUID PHASE PoLirME S M. KOVACH A BORIA-ALUMINA CATALYST Filed Aug. 24, 1962 RIZATION OF OLEFINS USING VAPOR PHASE FUN l D PHASE RUN 2 VOL. /0 OVERHEAD INVENTOR.

ATTORNEY? United States Patent LEQUllD PHASE POLYMERZZA'HGN {3F GLEFlNfS USING A BQRHA-ALUP '1]. A CATALYST Stephen M. Kovach, Highland, Ind, assignor to Sinclair Research, Inc., Wilmington, Del., a corporation of Delaware Filed Aug. 24, 1962, Ser. No. 219,219 5 Claims. (Cl. 268-68315) This invention relates to a process for the selective polymerization of olefins to polymers whose molecularweights correspond to multiple units of the olefin and in particular, the olefin tetramer, pentamer and hexamer. Specifically, the present invention is directed to the selective polymerization of olefins containing 3 to 12 carbon atoms, and particularly to the selective polymerization of olefins containing 3 and 4 carbon atoms.

Olefins can be polymerized over known polymerization catalysts such as phosphoric acid to yield polymers of varying molecular weight. For instance, in propylene polymerization the propylene dimer and trimer fractions are utilized in motor gasoline and propylene tetramer and tridecene as alkylating agents in the manufacture of alkylaryl detergents. The tetramer and tridecene are actually composed of olefin polymers with varying molecular weights which give an average carbon number of C and C respectively. Processing propylene under typical commercial conditions (vapor-phase) over one of the common commercial catalysts, e.g. a calcined composite of phosphoric acid on kieselguhr, liquid phosphoric acid film on quartz, liquid acids such as phophoric, sulfuric, etc. however, yields a nondescript product containing olefin polymers in the molecular Weight range of C through C and contains substantial amounts of intermediate molecular weight olefin polymers.

The trend in alkylaryl detergent manufacture is currently towards the use of higher molecular weight olefins such as the tetramers and hexamers. Unfortunately, the yield of high molecular weight olefins is low over commerical catalysts such as phosphoric acid on kieselguhr and necessitates recycle operation. In propylene polymerization one does not obtain the selective polymerization of propylene to the pentamer and hexamer. Many other catalyst systems investigated in the vapor-phase polymerization of propylene afford no better product distribution and yield than obtained from use of the phosphoric acid on kieselguhr catalyst.

A process has now been discovered whereby C to C1 olefins, particularly the C O, olefins can be polymerized to high selective yields of the dimer, trimer, tetramer, pentamer, hexamer and higher homologues with high conversions of olefin. Moreover, the liquid olefin products of this process correspond to an unusually large extent in molecular weights to multiple units of the olefin, that is, there is a substantial reduction in intermediate molecular weight olefin polymers, and preferably the product contains little if any intermediate molecular weight olefin polymers.

In accordance with the process of the present invention the olefin is polymerized over a select catalyst containing boria and alumina while employing a particular set of operating conditions. To obtain the desired results, it is important that the conditions of temperature and pres sure employed in the process be such that the olefin remains essentially in the liquid phase. This necessitates maintaining processing temperatures below the critical temperature of the olefin, for instance in the polymerization of propylene a temperature of about 198 F., and operating pressures above the vapor pressure of the olefin at the processing temperature under essentially anhydrous conditions. In the polymerization convenient reaction temperatures are below about 200 F., for instance about 0 to 197 F. for propylene, preferably about 70 to 180 F., and the pressure often ranges from about 0 to 2000 p.s.i.g., preferably about 200 to 800 p.s.i.g. Space velocities in the range of about 0.1 to 20 LHSV (liquid hourly space velocity) have been found suitable but a space velocity of about 0.1 to 10 LHSV is preferred. When using a boria-alumina catalyst, the principal products are the trimers, tetrarners and pentarners of the olefin feed. The desired polymer fraction can be recovered from the liquid olefin product by any suitable means such as fractionation.

Due to the exothermicity of the polymerization reaction and the narrow temperature operating range, it is preferred to employ internal means as heat sinks. This can be accomplished for instance by employing inert hydrocarbon and catalyst diluents. The catalyst diluents are solid and the hydrocarbon diluents are liquid at the reaction conditions. The hydrocarbon diluent can be any hydrocarbon, unable to undergo polymerization, condensation, alkylation, etc-under the process conditions. This would encompass paraffins, naphthenes, highly-substituted aromatics, etc. The preferred inert hydrocarbon diluent is propane. The inert hydrocarbon diluent reduces the concentration of olefin in the liquid phase and at the catalyst surface and often acts as a heat sink. If aromatics are used as a diluent, benzene, toluene, xylene and other monO- and (til-substituted) aromatics are undesirable since they may undergo alkylation with the olefin under the mild conditions required for selective polymerization. The aromatic solvent should be non-alkylatable under the conditions utilized, ie, they should be highly substituted as for instance tri or tetra or more substituted benzenes. The choice of solvent will depend on factors such as the olefin feed, etc. which tend to maximize polymerization and minimize alkylation. Suitable inert catalyst diluents are any materials not supporting the polymerization, e.g. tabular alumina and material similar to that found in Table III, below, nor which would destroy the polymerization activity of the catalyst. The amount of liquid diluent may be present in the range of about 0 to 10 or more, preferably about 0.5 to 2, volumes of diluent to about 1 volume of the olefin. The solid diluent may be present in a volume ratio of about 0 to about 10, preferably about 1 to 3, volumes of the solid diluent to about 1 volume of the catalyst. In addition, external sources of cooling may be utilized such as circulating cold water, cold feed, air, etc.

The catalyst of the present invention is boria on alumina. The boria is present on the alumina support in catalytically effective amounts. Generally this amount will fall Within the range of about 2 to 20% by Weight, preferably about 3 to 15% by weight. The catalyst sup- 'port'of the present invention is an activated or a gammafamily alumina e.g. gamma, eta, etc., such as those derived by calcination of amorphous hydrous alumina, alumina monohydrate, alumina trihydrate or their mixtures. The catalyst base most advantageous is a mixture predominating, for instance, in about to weight percent, in one or more of the alumina (trihydrates) i.e. bayerite I, bayerite ll, (randomite or nordstrandite) or gibbsite, and about 5 to 35 weight percent of alumina monohydrate (-boehmite), amorphous hydrous alumina or their mixture. The alumina support can contain small amounts of a solid oxide such as silica, magnesia, activated clays (such as kaolinite, montmorillonite, halloysite, etc.), titania, zirconia, etc. or their mixtures.

The catalysts can be prepared by impregnation using a water-soluble compound of the catalyst component. The boria can be added to the catalyst base in any stage of its preparation; however, it is frequently added to the catalyst after it has been formed by tabletting or extrusion and calcined. A suitable water soluble boria compound is boric acid.

To further illustrate the process of the present invention and demonstrate the importance of operating in the liquid phase as opposed to the vapor phase, Example I is included.

Example I Propylene was polymerized in the liquid phase over the catalyst of the present invention. For comparison, a run was also made in the vapor phase over the catalyst. The specific conditions employed and the results obtained are shown in Table I below. Run 1 represents a vaporphase operation and run 2, a liquid phase operation.

The data show that in run 1, which was made in the vapor-phase, large amounts of the product lay intermediate to the propylene trimer, tetramer, and pentamer ranges. In contrast, the product of run 2, made in the liquid phase, lay principally within the boiling range for propylene trimer, tetrarner and pentamer with only a small amount boiling intermediate these materials. This is further illustrated if one plots overhead temperature vs. volume percent overhead as shown in the figure for a boria-alumina catalyst. Directing attention to the figure it can be readily seen that in the vapor-phase run a straight line or nearly constant slope is' obtained on plotting distillation temperatures and overhead. Plotting the distillation data from the liquid phase run yields plateaus corresponding to propylene trimer, tetramer and pentamer.

Examples II and III are included to illustrate the importance of employing the defined catalysts in the process of the present invention.

Example II Propylene polymerizations were conducted under the conditions shown in Table 11 below employing the fol lowing catalysts:

10% B 0 on A1 0 B 0 alone, and Algog alone. The

conversion obtained with each catalyst is shown in Table TABLE II [Conditions: F., 800 p.s.i.g., l LHSV] Run 2 7 9 Catalyst lo /11320:, B10 Alz03 C Conversion 81 1 (l The data of Table 11 show that the alumina support and boria, when employed alone showed little or no activity towards the selective polymerization of propylene in the liquid phase. However, incorporating boria on the alumina yielded an excellent catalyst for selective polymerization.

Example III Various catalysts identified in Table III and known to be active for the vapor phase polymerization of propylene, were employed in propylene polymerizations under the liquid phase conditions shown in Table III. The propylene conversion obtained with each catalyst is also shown in Table 111.

The data of Table III demonstrate that although the catalyst may be active for the vapor-phase polymerization of propylene, they show no activity under the conditions of the present invention.

Example IV These runs show that the choice of solvent may affect the polymerization reaction and that for polymerization of the olefin the choice of solvent may depend on the olefin feed.

TABLE IV [Catalyst 10% Bails-A1203] Wt. Percent of Polymer The catalyst of the present invention possesses unique fouling and regenerating features. By operating at low temperatures (at room temperature) this catalyst becomes deactivated not by carbon laydown on catalyst but loses activity by the plugging of the catalyst pores by heavy polymeric material. Polymerization activity can be restored, however, by Washing the catalyst with a suitable paraffin or aromatic hydrocarbon solvent as, for instance, n-pentane or benzene. If solvent washing fails, reactivation can be brought about by heat-treating the catalyst to 400 to 700 F. and purging with an inert gas such as nitrogen. This high temperature purge drives the heavy polymeric material out of the pores of the catalyst depositing only a small amount of carbon on the catalyst without loss in polymerization activity. This is better illustrated in the following sequence of runs in Table V below.

TABLE V [Catalyst: Bzoa-Alzos. Polymerization conditions: 80 F., 800

p.s.i.g., l LHSV, propylene feed] Run 16 17 18 Catalyst from Run Catalyst from Fresh 16 adsorbed polymer Run 17 Purge Catalyst left on Cat. with N2 at overnight 700 F.

(Is-Conversion, Wt.

percent 80 19 80 Wt. percent Product:

C5- 7 3 Ct- 25 C12- 28 C- 18 C15- 2O I claim:

1. A proces for the selective polymerization of C to C olefins to polymers whose molecular Weights correspond to multiple units of said olefin which consists essentially of polymerizing a feed consisting essentially of said olefin at a temperature below about 200 F. and a pressure of about 0 to 2000 p.s.i.g. in the liquid phase in contact with a catalyst consisting essential of about 2 to by weight of boria supported on activated alumina.

2. The process of claim 1 wherein the temperature is about to 180 F. and the pressure is about 200 to 800 p.s.i.g. and the olefin is propylene.

3. The process of claim 2 wherein the amount of boria on the alumina support is about 3 to 15% by Weight.

4. The process of claim 1 wherein the olefin is isobutylene.

5. The process of claim 1 wherein the olefin is propylene.

References Cited by the Examiner UNITED STATES PATENTS 2,301,342 11/1942 Sumerford 260683.2 2,989,574 6/1961 Pfefierle et al. 260683.44 3,054,836 9/1962 Hervert et al. 260-671 3,217,060 11/1965 Hervert et a1 260683.2

PAUL M. COUGHLAN, JR., Primary Examiner.

DANIEL E. WYMAN, Examiner. 

1. A PROCESS FOR THE SELECTIVE POLYMERIZATION OF C3 TO C12 OLEFINS TO POLYMERS WHOSE MOLECULAR WEIGHTS CORRESPOND TO MULTIPLE UNITS OF SAID OLEFIN WHICH CONSISTS ESSENTIALLY OF POLYMERIZING A FEED CONSISTING ESSENTIALLY OF SAID OLEFIN AT A TEMPERATURE BELOW ABOUT 200*F. AND A PRESSURE OF ABOUT 0 TO 2000 P.S.I.G. IN THE LIQUID PHASE IN CONTACT WITH A CATALYST CONSISTING ESSENTIAL OF ABOUT 2 TO 20% BY WEIGHT OF BORIA SUPPORTED ON ACTIVATED ALUMINA. 